prevent duplicate EKF logging

vehicle code sometimes tries to log the same data twice

libraries/AP_NavEKF2/AP_NavEKF2.h

@@ -476,6 +476,9 @@ private:
 
     // time at start of current filter update
     uint64_t imuSampleTime_us;
+
+    // last time of Log_Write
+    uint64_t lastLogWrite_us;
     
     struct {
         uint32_t last_function_call;  // last time getLastYawResetAngle was called

libraries/AP_NavEKF2/AP_NavEKF2_Logging.cpp

@@ -288,6 +288,12 @@ void NavEKF2::Log_Write()
         return;
     }
 
+    if (lastLogWrite_us == imuSampleTime_us) {
+        // vehicle is doubling up on logging
+        return;
+    }
+    lastLogWrite_us = imuSampleTime_us;
+
     const uint64_t time_us = AP::dal().micros64();
 
     // note that several of these functions exit-early if they're not

libraries/AP_NavEKF3/AP_NavEKF3.h

@@ -534,6 +534,9 @@ private:
     // time of last lane switch
     uint32_t lastLaneSwitch_ms;
 
+    // last time of Log_Write
+    uint64_t lastLogWrite_us;
+
     struct {
         uint32_t last_function_call;  // last time getLastYawResetAngle was called
         bool core_changed;            // true when a core change happened and hasn't been consumed, false otherwise

libraries/AP_NavEKF3/AP_NavEKF3_Logging.cpp

@@ -352,6 +352,11 @@ void NavEKF3::Log_Write()
     if (activeCores() <= 0) {
         return;
     }
+    if (lastLogWrite_us == imuSampleTime_us) {
+        // vehicle is doubling up on logging
+        return;
+    }
+    lastLogWrite_us = imuSampleTime_us;
 
     uint64_t time_us = AP::dal().micros64();